As a display device having a display panel protected by a transparent surface material (a protective plate), the following one is known. For example, a display device is known wherein a display panel and a protective plate are bonded via an adhesive sheet (Patent Documents 1 and 2).
Bonding of the display panel and the protective plate may be carried out by the following method so that voids will not remain at the interface between the adhesive sheet and the display panel or the protective plate.
For example, the bonding may be carried out by a method wherein the display panel and the protective plate are bonded via an adhesive sheet in a reduced pressure atmosphere, and then the atmosphere is returned to the atmospheric pressure atmosphere.
According to such a method, as shown in FIG. 9, even if an independent void 110 remains at the interface between an adhesive sheet 100 and a display panel 50 or a protective plate 10 at the time when the display panel 50 and the protective plate 10 are bonded via the adhesive sheet 100 in a reduced pressure atmosphere, if the atmosphere is then returned to the atmospheric pressure atmosphere, the volume of the void 110 decreases, and the void 110 will eventually disappear, due to differential pressure between the pressure in the void 110 (the reduced pressure) and the pressure exerted to the adhesive sheet 100 (the atmospheric pressure).
However, as shown in FIG. 10, a void 120 open to exterior is likely to be formed along the periphery of the adhesive sheet 100 in many cases, when the display panel 50 and the protective plate 10 are bonded via the adhesive sheet 100. When the assembly having the display panel 50 and the protective plate 10 bonded via the adhesive sheet 100 in a reduced pressure atmosphere, is returned to the atmospheric pressure atmosphere, the pressure in the void 120 open to exterior is also returned to the atmospheric pressure, whereby the volume of the void 120 will not decrease, and the void 120 will remain.
Further, in such a method, after bonding the adhesive sheet to one of surface materials i.e. the display panel and the protective plate, it is necessary to bond the remaining surface material to the adhesive sheet. That is, the bonding step is required to be carried out twice, whereby the bonding of the display panel and the protective plate becomes cumbersome.